> When I plot a survival fit using rpart for the classification tree, for each
> node, there is a decimal based number above the event/total. I tried to see if
> it's the exponential ratio or logrithmics, neither seem to be the case. I'm
> wondering if anyone knows what they are.
---------
It is an estimate of the event rate, using a Baysian shrinkage argument
(#events +a) / (n +b) *c
To understand how the constants a and b are chosen, you need to read the
detailed documentation (as pointed out already by Brian R). The constant c is
chosen to make the printed "rate" of the top node equal to 1. This last is
done
just to make it easier to scan the tree -- one can easily see that the rate is,
say, 20% lower in some particular node than for the data set as a whole.
Terry Therneau
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